Resinous composition containing polyesterepoxide resin adduct and etherified aminaldehyde resin

ABSTRACT

A resin composition suitable for use as paints is prepared by blending a polyfunctional high-molecular-weight linear polyester having a number average molecular weight of at least about 6,000 with an amino resin generally known as aminoplast or a polyisocyanate such as aliphatic or aromatic diisocyanate. The polyfunctional polyester is obtained by reacting a linear polyester having a number average molecular weight of about 1,000 to about 8,000 and a ratio of the terminal carboxyl group to the terminal hydroxyl group of at least 1 with a diepoxide at the epoxy group to the terminal carboxyl group ratio of from 0.5 to 2. The composition can give a baked film having excellent hardness, adhesion, chemical resistance, soiling resistance, and impact resistance.

Elite States atet 1 Murakami et al.

[ 1 March 6, 1973 [75] Inventors: Yoichi Murakami; Hikaru Watanabe, bothof Amagasaki-shi, Japan [73] Assignee: Dainippon Ink and Chemicals, In-

corporated, Tokyo, Japan [22] Filed: Jan. 19,1971

[2]] Appl. No.: 107,857

[30] Foreign Application Priority Data Jan. 22,1970 Japan ..45/5436 [52]U.S. Cl. ,.260/834, 260/37 EP, 260/39 R,

260/39 P, 260/830 P, 260/835 [51] Int. Cl ..C08g 45/10, C08g 45/14 [58]Field of Search ..260/834 [56] References Cited UNITED STATES PATENTS3,655,817 4/1972 Lohse .260/834 3,410,926 11/1968 ....260/834 3,173,9713/1965 ..260/834 2,591,539 4/1952 ..260/834 2,850,475 9/1958 Greenlee..260/834 3,097,183 7/1963 Drubel ..260/834 3,154,427 10/1964 Forrest..260/834 3,493,414 2/1970 Hastings... ..260/834 3,507,820 4/1970 Maeda..260/834 3 ,548,026 12/ 1 970 Weisfeld ..260/834 3,600,459 8/1971 Vasta..260/834 Primary ExaminerPaul Lieberman Attorney-Sherman & Shalloway[57] ABSTRACT A resin composition suitable for use as paints is preparedby blending a polyfunctional high-molecularweight linear polyesterhaving a number average molecular weight of at least about 6,000 with anamino resin generally known as aminoplast or a polyisocyanate such asaliphatic or aromatic diisocyanate. The polyfunctional polyester isobtained by reacting a linear polyester having a number averagemolecular weight of about 1,000 to about 8,000 and a ratio of theterminal carboxyl group to the terminal hydroxyl group of at least 1with a diepoxide at the epoxy group to the terminal carboxyl group ratioof from 0.5 to 2. The composition can give a baked film having excellenthardness, adhesion, chemical resistance, soiling resistance, and impactresistance.

2 Claims, No Drawings RESINOIJS COMPOSITION CONTAINING POLYESTER-EPOXIDERESIN ADDUCT AND ETHERIFIED AMIN-ALDEIIYDE RESIN This invention relatesto a resin composition suitable for use as a paint which comprises apolyfunctional high-molecular-weight linear polyester and an amino resinor a polyisocyanate.

It is known to use as a baking paint a resin composition comprising anamino resin and a high-molecularweight linear polyester obtained by theglycol-removing reaction of a diglycol ester of a dibasic acid. Thisresin composition, however, cannot give a coated film of excellentproperties since it is difficult to induce a cross-linking and curingreaction between the polyester and the amino resin.

An object of this invention is to provide a resin composition consistingpredominantly of a high-molecularweight polyester free from suchdefects.

It has been found that this object of the invention can be achieved by aresin composition prepared by blending an amino resin or apolyiso-cyanate with a polyfunctional high-molecular-weight linearpolyester (to be referred to simply as polyfunctional polyesterhereinafter) obtained by reacting a diepoxide with a linear polyester inwhich the ratio of the terminal carboxyl group to the terminal hydroxylgroup is at least 1.

The linear polyester which is the startingmaterial of the polyfunctionalpolyester is prepared from an optional dicarboxylic acid and an optionalsaturated dihydric alcohol, and is a linear polyester having a numberaverage molecular weight of from about 1,000 to about 8,000 in which theratio of the terminal carboxyl group to the terminal hydroxyl group isat least 1. The linear polyester may be those in which both ends arecarboxyl groups. The reaction for producing the polyfunctional polyestercan be performed either by the melting method or by the solvent method.The reaction can also be carried out in the presence of any knownesterification catalyst.

The dicarboxylic acid that can be used as a material to produce thelinear polyester includes, for instance, saturated aliphatic or aromaticdicarboxylic acids such as oxalic acid, malonic acid, succinic acid,glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid,sebacic acid, brassylic acid, a-butyl-a-ethylglutaric acid,a,B-diethyl-succinic acid, phthalic anhydride, isophthalic acid, orterephthalic acid. Such dicarboxylic acids are described, for instance,in the specification of U. S. Pat. No. 3,236,812. These acids may beused conjointly with C alkyl esters of these acids.

Examples of the saturated dihydric alcohol that can be used as. theother material to produce the linear polyester preferably includelow-molecular-weight saturated aliphatic dihydric alcohols such asethylene glycol, diethylene glycol, l,3-propylene glycol, 1,2- propyleneglycol, l,4-butylene glycol, 1,3-butylene glycol, 1,5-pentanediol,1,4-pentanediol, l,3-pentanediol, 1,6-hexanediol, 1,7heptanediol,2,2-dimethyl- 1,3-propanediol, l,8-octanediol or 1,20-eicosanediol.These dihydric alcohols are described, for instance, in thespecification of U. S. Pat. No. 3,236,812. Lowmolecular-weight alicyclicdihydric alcohols such as 1,4-cyclohexane dimethanol or hydrogenatedbisphenol A may also be used as the saturated dihydric alcohol.

When the solvent method is used to prepare the linear polyester, anorganic solvent, for example, aromatic hydrocarbons such as xylol,toluol and benzene or ketones such as methyl ethyl ketone, methylisobutyl 5 ketone, cyclohexanone, or isophorone may be used. It is alsopossible to use mixed solvents consisting of these with esters such asethyl acetate, butyl acetate and cellosolve acetate. These solvents canalso be used in the manufacture of the polyfunctional polyester.

The polyfunctional polyester referred to in the present invention is alinear high-molecular-weight polymer having a number average molecularweight of about 6,000 or more, and is obtained by ring-openingesterification reaction of a linear polyester with a diepoxide with theratio of the epoxy group to the terminal carboxyl group being maintainedwithin the range of 0.5 to 2.

As the polyfunctional polyester, those having a considerably highmolecular weight can be used, but the preferred polyfunctionalpolyesters are those having a number average molecular weight of atleast about 6,000. There is no strict limitation in this regard.Commercially feasible polyfunctional polyesters have a number averagemolecular weight of up to about 100,000.

When the linear polyester is reacted with the diepoxide in an amountsuch that the ratio of the epoxy group to the terminal carboxyl group isoutside the range of 0.5 to 2, only a polyfunctional polyester havinglow molecular weight is obtained. A cured film obtained by using suchpolyfunctional polyester having low molecular weight is inferior in filmproperties, and is not feasible.

The ring-opening esterification reaction is carried out by heating thelinear polyester and the diepoxide. directly or after dissolving them inan organic solvent, at a temperature of not more than 200 C., preferablybelow 150 C. When the reaction temperature is over 200 C., the hydroxylgroup in the molecule of the resulting polyfunctional polyesterundergoes an esterification reaction with the terminal carboxyl group ofthe unreacted linear polyester, which tends to cause the gellation ofthe reaction system. On the other hand, when a linear polyester having amolecular weight of less than 1,000 is used, the amount of the diepoxidenecessary for increasing the molecular weight of the polyester becomeslarge, and consequently, the resulting polyfunctional polyester has toomany functional groups. A composition obtained by blending an aminoresin or polyisocyanate with such polyfunctional polyester is notdesirable with respect to the efficiency of painting work andsolubility. Linear polyesters having a molecular weight of over 8,000are unsuitable for use in the present invention since the resultinghighmolecular-weight polyesters have too few functional groups.

The diepoxide necessary for obtaining the polyfunctional polyester isany compound which has in its molecule two epoxy groups reactive withthe carboxyl groups. Examples of the diepoxide include condensationproducts between bisphenol-A and epichlorohydrin such as Epikote 828,Epikote 1001, Epikote 1004, Epikote 1007 and Epikote 1009 (products ofShell Petroleum Co.); ester-type diepoxides such as diglycidylphthalate, diglycidyl terephthalate, diglycidyl adipate, diglycidylglutarate, diglycidyl succinate, diglycidyl oxalate, and diglycidylazepate; alicyclic diepoxides such as limonene dioxide,dicyclopentadiene dioxide, vinyl cyclohexane dioxide, or3,4-epoxy-o-methylcyclohexylmethyl-3,4-epoxy-6- methylcyclohexanecarboxylate; and aliphatic ether type diepoxides, such as ethyleneglycol diglycidyl ether, diethylene diglycol diglycidyl ether,triethylene glycol diglycidyl ether, 1,2-propylene glycol diglycidylether, 1,4-butylene glycol diglycidyl ether, 1,5-pentanediol diglycidylether, or glycerine diglycidyl ether. These diepoxides are described,for instance, in U. S. Pat. No. 3,245,925 and U. S. Pat. No. 3,378,601.

The resin composition of the present invention is obtained by blendingan amino resin or a polyisocyanate with this polyfunctional polyester.The preferred weight ratio of the polyfunctional polyester to the aminoresin or polyisocyanate is 95 to 75 25. If the ratio is outside therange of 99 l to 60 40, a film obtained by heating and curing thecomposition does not have sufficient hardness, and is poor in adhesion,resistance to solvent, etc, since the amount of the polyfunctionalpolyester becomes extremely large or the amount of the amino resin orpolyisocyanate becomes too large. In other words, when the amount of thepolyfunctional polyester is extremely large, the cross-linking andcuring of the composition is not sufficient, and when the amount of theamino resin or polyisocyanate is large, the number of the functionalgroups is excessive and results in a poor film.

The amino resin to be blended with the polyfunctional polyester isobtained by condensing a polyamino compound of low molecular weight withformaldehyde, paraformaldehyde or a compound which generates suchaldehyde, or further etherifying the resulting resin with an alcohol.The resins which are generally called aminoplast are all included withinthis amino resin. Specific examples of the amino resin that is used inthe invention include the condensation products between polyaminocompounds of low molecular weight such as melamine, benzoguanamine,acetoguanamine, triazine, diazine, guanidine, guanamine, urea, thiourea,or ethyleneurea and formaldehyde, paraformaldehyde or a compound whichgenerates such aldehyde; and the etherification products of thesecondensation products with alcohols having not more than 8 carbon atoms.The examples of such etherification products are methyletherifiedmelamine resin, butyletherified melamine resin, and butyletherifiedbenzoguanamine resin. These examples are described in the specificationof U. S. Pat. No. 3,382,294. The amino resins which are particularlypreferred in the present invention are the etherification products ofthe aforementioned condensation products with alcohols having not morethan 8 carbon atoms.

The examples of the polyisocyanate that can be used in the presentinvention are described in the specification of U. S. Pat. No.3,401,135, and include aromatic and aliphaticdiisocyanates such as2,4-tolylenediiso cyanate, 2,o-tolylenediisocyanate, meta-xylenediisocyanate, para-xylene diisocyanate, diphenylmethane-4,4-diisocyanate, 3,3-dimethyl-4,4-biphenylene diisocyanate,hexamethylene-l,6-diis0cyanate, or butylene-l ,2-diisocyanate; and theaddition products between these diisocyanates and polyhydric alcohols oflow molecular weight such as ethylene glycol, propylene glycol,trimethylol propane, glycerine, hexanetriol, sorbitol, mannitol orsorbitan. There can also be used block polyisocyanates obtained bytreating the aforementioned isocyanates with a blocking agent such asphenols, tertiary alcohols, active methylene compounds, oximes, iminesand lactams. Alicyclic diisocyanates such as isophorone diisocyanates,and polymers of the aforementioned diisocyanates can also be used.

The resin composition of the present invention can be diluted with asolvent prior to using it in various applications. Examples of thesolvents that can be used for this purpose are, for example, alcoholssuch as methanol, ethanol, n-butanol, isobutanol, or butyl cellosolve,chlorinated hydrocarbons such as chloroform, trichloroethylene, ordichlorobenzene, ethers such as dioxane and tetrahydrofuran, anddimethyl formamide, in addition to the solvents mentioned above whichcan be used in the synthesis of the linear polyester. Mixtures of thesesolvents in optional combinations are suitably used in the presentinvention.

When the resin composition of the invention is used for instance as apaint, it is possible to incorporate a pigment in it. The pigments thatcan be used may be organic or inorganic, and include inorganic pigmentssuch as clay, talc, zinc flower, lithopone, red iron oxide, red lead,chrome yellow, chrome green, Prussian blue, or carbon black, and organicpigments of the azo, phthalocyanine, quinacridone, anthraquinone,dioxazine, thioindigo, and perylene series.

When heated and cured, the resin composition of the invention forms afilm which has excellent properties required of the film, such assolvent resistance, hardness, flexibility, resistance to soiling,adhesion, corrosion resistance, and chemical resistance. The resincompositions of the invention comprising the polyfunctional polyestersand polyisocyanates (other than the block polyisocyanates) can be curedat room temperature to form a film having excellent properties.

The resin composition of the invention may be in the form of a solutionin a solvent, or in the form of powders. Such powdery resin compositioncan be prepared by blending a polyfunctional polyester substantiallyfree of solvent with an amino resin such as the butyletherified melamineresin, methyletherified melamine resin or butyletherified benzoguanamineor the block polyisocyanate. The polyfunctional polyester substantiallyfree of solvent can be prepared, for example, by heating a linearpolyester and a diepoxide in the absence of a solvent, or concentratinga solution containing a polyfunctional polyester under reduced pressurefollowed by drying by a flush dryer, or by adding such solution dropwiseto a non-solvent to coagulate it, followed by drying.

The resin composition of the invention can be used advantageously aspaints, films, etc., especially the paints.

The invention will further be described in detail by the followingExamples which are presented for illustrative, rather than limitative,purposes. Unless otherwise specified, all parts and percentages are byweight.

EXAMPLE 1 Neopentyl glycol (17.2 parts), 10.2 parts of ethylene glycol,29.1 parts of dimethyl terephthalate and 0.009 part of zinc acetate wereput into a flask equipped with a reflux condenser. With stirring in astream of an inert gas, the materials were heated at 210 C. for about 2hours. Methanol of the theoretical amount distilled out. To the reactionmixture 24.9 parts of isophthalic acid were added, and the mixture wasmaintained for 3 hours at 210 C. For promoting dehydration, 3 parts ofxylol were added dropwise under reflux. The reaction was furthercontinued for 5 hours while raising the reaction temperature graduallyto 230 C. to form a high-molecular-weight polyester having an acid valueof 24 and a hydroxyl value of 5.6. Its number average molecular weightcalculated was about 3,800. The resulting polyester was dissolved in amixed solvent of xylol/methyl isobutyl ketone/cyclohexanone (50/25/25)so that its solids content reached 50 percent, to give a resin solutionhaving a Gardner viscosity of P.

To 50 parts of the resin solution 1.1 parts of glycerine diglycidylether, parts of xylol, 5 parts of cyclohexanone and 0.027 part of2-methylimidazole were added, and the mixture was heated for 7 hours at1 C. A solution of polyfunctional polyester having a non-volatilecomponent content of 40.5 percent, an acid value of 1.9, and a Gardnerviscosity of Z, was obtained. It had a number average molecular weightof about 7 ,500.

Butyletherified melamine resin (having a nonvolatile component contentof 5011, a molecular weight of about 800 and a Gardner viscosity of A toD) was added to the solution of polyfunctional polyester at the ratio of15 of the former to 85 of the latter. Rutile titanium oxide was added tothe blend in an amount of 45 pigment percent, and the mixture was milledwith three rolls to form white enamel. The resulting white enamel wascoated on a 0.3 mm thick zinc iron plate by a bar coater to a baked filmthickness of 15 to 18 1., and

baked at 250 C. for 1 minute. As shown in Table 1, the

EXAMPLE 2 To parts of the polyester obtained in Example 1 1.1 parts ofglycerine diglycidyl ether was added, and they were reacted for 1 hourat 180 C. in the absence of a solvent and a catalyst. The product wasdissolved in a mixed solvent of xylol/methyl isobutylketone/cyclohexanone (50/25/25) so that its solids content reached 40percent, thereby forming a solution of a polyfunctional polyester havingan acid value of 2.5 and a Gardner viscosity of Z White enamel wasprepared in the same manner as described in Example 1 using the solutionof the polyfunctional polyester, and baked. The properties of the filmobtained were the same as those of the film obtained in Example 1.

EXAMPLE 3 Neopentyl glycol (21.3 parts), 12.7 parts of ethylene glycol,52 parts of isophthalic acid, 12 parts of sebacic acid and 0.08 part ofdibutyltin oxide were put in a flask equipped with a reflux condenser,and the materials were heated for 5 hours at 210 C. with stirring in astream of an inert gas. Four parts of xylol were added dropwise, and thereaction was further continued for 5 hours while raising the reactiontemperature gradually to 230 C. to form a high-molecular-weightpolyester having an acid value of 22 and a hydroxyl value of 1.8. Itsnumber average molecular weight calculated was about 4,700. Theresulting polyester was dissolved in a mixed solvent of xylol/methylisobutyl ketone/cyclohexanone (50/25/25) so that its solids contentreached 50 percent, to form a resin solution having a Gardner viscosityof M to N.

To 90 parts of this resin solution 3.4 parts of Epikote 828 (thebisphenol type diepoxide of Shell Petroleum Co.), 8.2 parts of xylol,5.9 parts of isobutanol and 0.048 part of 2-methy1imidazole were added,and the mixture was heated at 115 C. for 8 hours to form a solution ofresin having a non-volatile component content of 45.3 percent, an acidvalue of 1.8, and a Gardner viscosity of Z.,. lts number averagemolecular weight was about 11,000.

Using the resulting solution, white enamel was prepared in the samemanner as in Example 1, and baked. The resulting film had very goodproperties as shown in Table 1.

EXAMPLE 4 1n the same manner as set forth in Example 2, 29 parts of1,2-propylene glycol, 52 parts of isophthalic acid, 12 parts of adipicacid, and 0.08 parts of dibutyl tin oxide were reacted to form ahigh-molecular-weight polyester having an acid value of 37 and ahydroxyl value of 1.4. lts number average molecular weight calculatedwas about 2,900. The polyester was dissolved in xylol so that its solidscontent reached 50 percent to form a resin solution having a Gardnerviscosity of F.

To 50 parts of this resin solution 2.4 parts of diglycidyltetrahydrophthalate, 6.5 parts of xylol, 6.5 parts of isobutanol and0.03 part of 2-methyl imidazole were added, and the mixture was heatedfor 8 hours at 115 C. to form a resin solution having a non-volatilecomponent content of 41.0 percent, an acid value 1.2, and a Gardnerviscosity of Z;,. It had a number average molecular weight of about14,000.

White enamel was prepared in the same way as in Example 1 using thisresin solution, and baked. The resulting film had the excellentproperties as described in Table l.

EXAMPLE 5 COMPARATIVE EXAMPLE 1 lsophthalic acid (180 parts), 180 partsof adipic acid, 120 parts of trimethylol propane and 180 parts ofneopentyl glycol were heated at 180 C. for 2 hours and then at 220 C.for about 7 hours with stirring in a stream of an inert gas to form apolyester resin having an acid value of 8. The resulting polyester resinwas diluted with a mixed solvent of xylene/butyl cellosolve (9/1) sothat its non-volatile component content reached 60 percent. The solutionobtained had a Gardner viscosity of U-V and an acid value of4.5.

The resulting polyester resin solution, butyletherified benzoguanamineresin (non-volatile content of 60 t 1 percent, molecular weight of about600, and Gardner viscosity of A-C), and the butyletherified melamineresin used in Example 1 were blended with one another at a ratio of 80 l10 in terms of the solids content. The white enamel obtained was bakedin the same way as set forth in Example 1. The film obtained wasinferior to any of the films obtained in the foregoing Examples wererespect to hardness, flexibility, adhesion, corrosion resistance, andchemical resistance. It was also found inferior in hardness at lowtemperatures and roll coating operability.

COMPARATIVE EXAMPLE 2 Neopentyl glycol (26.1 parts), 25.4 parts ofethylene glycol, 29.1 parts of dimethyl terephthalate and 29.1 parts ofdimethyl isophthalate were put into a flask, followed by addition of0.018 part of zinc acetate. The mixture was heated for about 2 hours at210 C. with stirring in a stream of an inert gas. Methanol of thetheoretical amount distilled out, and the ester-interchange reaction wascompleted. The temperature was raised to 245 C., and the pressurereduced to 0.3 mmHg gradually. The reaction mixture was maintained for 1hour at 245 C., and then excess glycol was removed out of the reactionsystem by distillation. The temperature was raised to 275 C., and thereaction mixture was maintained at this temperature for 2 hours underthe pressure of 0.3 mmHg. The polyester formed was a substantiallyhydroxyl-terminated resin having a number average molecular weight ofgreater than 10,000.

The resulting resin was dissolved in methyl ethyl ketone so that itssolids content reached 30 percent. The solution of the resin was blendedwith the butyletherified melamine resin at a ratio of 85 in terms of thesolids content, and white enamel was prepared and baked in the samemanner as set forth in Example 1. The film obtained was inferior in filmproperties to any of those obtained in the Examples above, as will beseen from Table 1.

COMPARATIVE EXAMPLE 3 White enamel was prepared by blending the methylethyl ketone solution of the polyester obtained in Comparative Example 2with the addition product of diisocyanate and polyhydric alcohol used inExample 5 at a 5 ratio such that the hydroxyl/isocyanate ratio was 1 l;and was baked for 1 minute at 250 C. in the same manner as set forth inExample 1. The film obtained was inferior in the film properties to thefilm obtained in Example 5.

10 TABLE 1 Examples Nos.

Examples Comparative Examples Properties 1 3 4 5 1 2 3 Pencil hardness5H 3H 4H 4H 2H 3H 3H Impact strength 4+ -l+ i Bending impact test iAdhesion (cross cut;

adhesive tape peeling) 4+ H- H- Resistance to soiling (rouge) iResistance to sulfuric acid (10 24 hours) t Resistance to sodiumhydroxide l0 24 25 hours) i+ i i Resistance to xylol (rubbing test) H-Resistance to salt spray (100 hours) H- -H- -l+ t t Note: In the abovetable, the symbols represent the following. ++Excellent lGood tFair PoorVery poor What is claimed is:

1. A resin composition comprising a polyfunctional,high-molecular-weight linear polyester having a number average molecularweight of at least about 6,000 and an etherified amine-aldehyde resin,said polyfunctional polyester being obtained by reacting a linearpolyester derived from difunctional acids and diols said polyesterhaving a number average molecular weight of about 1,000 to about 8,000and a ratio of the terminal carboxyl group to the terminal hydroxylgroup of at least 1 with a diepoxide' at the ratio of theepoxy group tothe terminal carboxyl group on the polyester being from 0.5 to 2:1, thepolyfunctional high molecular weight linear polyester and the etherifiedamine-aldehyde resin being present at a ratio of 99:1 to 60:40.

2. The composition of claim 1 wherein said polyfunctionalhigh-m'olecular-weight linear polyester has a number average molecularweight of 6,000 to 100,000. 55 a: a: s a: s

1. A resin composition comprising a polyfunctional,high-molecular-weight linear polyester having a number average molecularweight of at least about 6,000 and an etherified amine-aldehyde resin,said polyfunctional polyester being obtained by reacting a linearpolyester derived from difunctional acids and diols said polyesterhaving a number average molecular weight of about 1,000 to about 8,000and a ratio of the terminal carboxyl group to the terminal hydroxylgroup of at least 1 with a diepoxide at the ratio of the epoxy group tothe terminal carboxyl group on the polyester being from 0.5 to 2:1, thepolyfunctional high molecular weight linear polyester and the etherifiedamine-aldehyde resin being present at a ratio of 99:1 to 60:40.